Steroid Endocrine Disruptors Hydroxy Derivative Of The Study

Endocrine Disrupting Chemicals(EDCs)is a series of widespread chemical compound in environment,which may interfere in the normal function of endocrine systems,affecting reproduction, development and behavior in human and wildlife,and also threating their survive or perish.As one of EDCs,steroids endocrine disrupting chemicals are a group of biologically active compounds that are synthesized from cholesterol and have a steroid ring in common.Steroids endocrine disrupting chemicals harm to organisms at very low concentrations with much more endocrine function than other EDCs.Gas Chromatography-Mass spectrometry(GC-MS)has been widely employed in determining EDCs in complex samples due to its high resolving power,excellent performance and low cost, especially when coupling with specific detectors,such as mass-spectrometer(MS).However,because of the high polarity and poor volatility of steroids endocrine disrupting chemicals,derivatization is required to produce more volatile products and to improve the method sensitivity and chromatographic separation previous to GC-MS analysis.In this paper,an improved simultaneous derivatization procedure for determination of the widespread and harmful steroids endocrine disrupting chemicals estrone(El),17-β-estradiol(E2), 17-α-ethynylestradoil(EE2)and estriol(E3)using GC-MS was developed.By using different derivatization reagents and catalysts,as well as controlling and optimizing derivatization conditions, including the amount of the derivatization reagents,temperature,time and the solvent,the steroids endocrine disrupting chemicals can be derivatized to the formation of TMS derivatives(derivatization reagents such as BSTFA,MSTFA,together with catalysts such as TMCS,TMSI)and TBS derivatives (derivatization reagents such as MTBSTFA,along with catalysts such as TBCS and TBSI).The reactivity of the derivatization reagents and catalysts towards the hydroxyl groups of the target compounds was compared and the influence of different derivatization parameters in the yield of the process was systematically investigated.Under the chosen derivatization reagents and catalysts,as well as the optimized derivatization conditions,the derivatization effects along with the sensitivity of GC-MS were discussed,and the calibration curves were also drawed.The developed derivatization procedure will resolve the key problem result from GC-MS,which is helpful for the detection of low concentration steroids endocrine disrupting chemicals in water environment.The main results and conclusion are presented as below.Before derivatization,the target compounds cannot be detected when the concentration ranges at ng/L level.However,under the optimal derivatization conditions,along with using derivatization reagents BSTFA and MSTFA,El,E2,EE2 and E3 were respectively derivatized as TMS-E1,di-TMS-E2,di-TMS-EE2 and tri-TMS-E3 with better results.The conclusion was that BSTFA and MSTFA can be used as TMS derivatization reagents for the simultaneous derivatization of E1,E2,EE2 and E3.The Instrumental Quantification Limit was 5pg/μL for EE2 and E3,while it was lpg/μL for E1 and E2 when using BSTFA as TMS derivatization reagents. However,when using MSTFA as TMS derivatization reagents,the result were better,for the Instrumental Quantification Limit of EE2 and E3,as well as E1 and E2 were 1pg/μL and 0.1pg/μL, respectively.In the procedure of TMS derivatization,better derivatization results were obtained when the the amount of BSTFA and MSTFA were 25μL and 20 MSTFA respectively for 100μL steroids standard mix solution at 0.01μg/μL.It was not need heat in BSTFA derivatization procedure for the useless of heat, but nor to MSTFA,because there was transform among EE2 derivaters in the process of heat,however, heat at 70℃for 30min can avoid this and obtain better derivatization results.The derivatization reaction was so speedy that we choose not to use catalysts.The derivaters of target compounds were stable because their RRF were no observable change when deposited 48h at-20℃.Pyridine was important in the procedure of TMS derivatization,not only for its role to avoid the transform among EE2 derivaters, but also for its action as solvent,nevertheless,other solvents such as methanol,ethyl acetate,acetone, dichloromethane,hexane were not suitable.In the procedure of TBS derivatization using MTBSTFA as derivatization reagents,E1 and E2 were derivatized as YBS-E1 and mono-TBS-E2,respectively,but E3 can be TBS derivatized,with unexpected that EE2 was derivatized as TBS-E1 in despite of any conditions,including the amount of MTBSTFA,catalysts,temperature,time and the solvent.So MTBSTFA were not suitable for the simultaneous derivatization of E1,E2,EE2 and E3.In addition,the mass spectrums of E1,E2,EE2 and E3,together with their derivaters were analysed.